Heat exchanger for powdered materials suspended in gases



May 20, 1969 e. v. TELYATNIKOV ET AL 3,444,623

HEAT EXCHANGER FOR POWDERED MATERIALS SUSPENDED IN GASES Filed March a, 1967 3 Tnven'lors ,wiw

United States Patent 3,444,628 HEAT EXCHANGER FOR POWDERED MATE- RIALS SUSPENDED IN GASES Garry Vladimirovich Telyatnikov, Gavanskaya ill. 10, kv.

3, and Evgeny Iosifovich Khodorov, Pl. Chernyshevskogo 7, kv. 5, both of Leningrad, U.S.S.R.; Anatoly Akindinovich Evtjutov, Oktyabrskaya 111. 24/1, kv. Denis Denisovich Skopa, Aljuminievaya ul. 17, kv. 29; Anatoly Alexeevich Chervinsky, Kamenskaya ul. 23, kv. Alexandr Vladimirovich Shilov, Aljuminievaya ul. 8, kv. 39; and Nina Mikhailovna Kazantseva, Ul. Gagarina 32, kv. 8, all of Kamensk-Uralsky, U.S.S.R.

Filed Mar. 6, 1967, Ser. No. 620,948 Int. Cl. F26b 17/10 US. Cl. 34-57 2 Claims ABSTRACT OF THE DISCLOSURE A powdered material heat exchanger having a heat exchanging column, a cyclone connected to the column in the direction of flow of the suspended powdered material, and a discharging chamber underneath the cyclone. The discharging chamber has two compartments divided by a partition which does not reach the bottom of the chamber. The first compartment is connected to the cyclone and contains a dense layer of powdered material discharged from the cyclone and which powdered material forms a seal at the bottom of the cyclone. The second compartment has means for fiuidizing the powdered material introduced from the first compartment, and as the powdered material is fluidized it exits through an outlet means.

This invention relates to heat exchangers for powdered materials suspended in gases and, more particularly, to heat exchangers for the recovery of heat from powdered material calcined in rotary kilns, such as alumina, or for the recovery of heat from waste gases of rotary kilns.

Known are heat exchangers for powdered materials comprised of at least one heat exchanging column and a cyclone with a discharging device, communicated in series with said column.

However, said heat exchangers provided with discharging devices, made in the form of gates do not insure a reliable seal for the cyclone or means of controlling the dwell time of the material in the heat exchanger. The gates are subjected to severe conditions when used at operating temperatures of 500 C. and higher and, moreover, do not make it possible to obtain a compact design of the heat exchanger comprised of several heat exchanging columns interconnected in series.

It is an object of the present invention to develop a discharging device for the cyclone, say, in heat exchangers, that would insure the continuous discharge of the cyclone and would simultaneously serve as a reliable seal of the cyclone, said seal involving no use of mechanical devices.

It is another object of the present invention to provide a seal in heat exchangers that would make it possible to control the dwell time of the material to complete requisite thermal and physical processes, such as the removal of water of hydration, and would also make for a compact arrangement of the heat exchanger comprised of a number of heat exchanging columns interconnected in series.

In accordance with the aforesaid and other objects, in the present heat exchanger for powdered materials suspended in gases, which is comprised of at least one heat exchanging column and a cyclone with a discharging device interconnected in series with said column, the cyclone discharging device, according to the invention, is a chamber disposed beneath the cyclone, the processed material "ice being fluidized and maintained in the state of fluidization in said chamber, and the seal of the cyclone being provided by the processed material that is discharged from the cyclone and contained in said chamber.

Other objects and advantages of the present invention will become apparent from the description presented hereinbelow and appended drawings, wherein:

FIG. 1 is a general view of a heat exchanger with a cyclone discharging chamber, according to the invention;

FIG. 2 is a modification of the cyclone discharging chamber, according to the invention; and

FIG. 3 presents the heat exchanger comprised of a number of series-connected heat exchanging columns, according to the invention.

Described hereinbelow is a heat exchanger for the recovery of heat from a powdered material, for example, alumina, calcined in rotary kilns.

The heat exchanger is comprised of a heat exchanging column 1 (FIG. 1), a cyclone 2 and a cyclone discharging chamber 3, all three being interconnected. In the bottom part of heat exchanging column 1, provision is made for an opening 4 connected to a gas inlet branch pipe 5, through which cooling air is fed into said column 1, as indicated by arrow A.

In the side portion of column 1, close to the bottom of said column, there is disposed a passage 6 intended for feeding calcined alumina into said column in the direction indicated by arrow B.

Cyclone 2 communicates with heat exchanging column 1 via a passage 7. In the top portion of cyclone 2, provision is made for a branch pipe 8, through which heated air is discharged, while the bottom portion of cyclone 2 terminates in a passage 9, which protrudes into discharging chamber 3 disposed beneath cyclone 2.

A side portion of discharging chamber 3 is furnished with an outlet port joined to an overflow branch pipe 10, through which the cooled alumina is sent to subsequent processing stages. In the bottom of discharging chamber 3, provision is made for an air distributing device 11. Pressurized air is delivered into chamber 3 via the branch pipe of said device 11 in the direction indicated by arrow C with a view of fluidizing the alumina and maintaining it in the state of fluidization. The lower end of passage 9 protruding into discharging chamber 3 is located below the inlet opening of overflow branch pipe 10.

In another embodiment of the present invention, the cyclone discharging chamber can be made in the form of a chamber 3' (FIG. 2) divided into two compartments 13 and 14 by means of a partition 12 that does not reach the bottom of chamber 3'.

Compartment 14 of chamber 3' is furnished with an air distributing device 11 and overflow branch pipe 10'.

Compartment 13 of chamber 3' is disposed beneath cyclone 2 and communicates with said cyclone via a passage 9', or is connected directly to the bottom of said cyclone.

The heat exchanger according to the invention operates as follows.

Calcined alumina enters heat exchanging column 1 via passage 6.

Cooling air flows at a certain rate via branch pipe 5 and opening 4 into heat exchanging column 1 and entrains and suspends the incoming alumina in the direction indicated by arrows A and B through passage 7 into cyclone 2, in which solid particles of the alumina are separated from the air. Heat exchange between alumina and air occurs, when said components travel concurrently, in heat exchanging column -1 and, to some extent, in cyclone 2. The cooled alumina travels in the direction indicated by arrow B and enters discharging chamber 3 via passage 9, whilst the heated air is drawn off in the direction indicated by arrow A through branch pipe 8.

Pressurized air is fed via a branch pipe of the air distributing device 11 into discharging chamber 3 where it fluidizes the cooled alumina discharged from cyclone 2.

As the fluidized bed of alumina is being formed, it fills chamber 3 and flows through overflow branch pipe 10 in the direction indicated by arrow B for subsequent processing.

Since the end of passage 9 protruding into discharging chamber 3 is located below the inlet of overflow branch pipe 10', the end of passage 9 is immersed in the fluidized alumina bed formed in chamber 3, thereby forming a reliable hydraulic seal which precludes the penetration of the flow of air from the cyclone.

Thus, the presence of fluidized alumina in discharging chamber 3 makes it possible to effect continuous discharging of the cyclone to create a seal with a view to insure high elficiency of dust catching in the cyclone, and is instrumental in controlling, within a wide range, the dwell time of alumina in the heat exchanger at temperatures required for the completion of thermal and physical processes, such as the removal of water of hydration. This control is attained by varying both the height of the fluidized bed and the amount of pressurized air delivered into the discharging chamber with a view to produce said fluidized bed.

The above-described operation may also be performed by a modified discharging chamber 3 (FIG. 2), wherein compartment 1 3 of said chamber 3' is intended for collecting the trapped material, such as alumina, which seals the cyclone, while in compartment 14 of the chamber said trapped material is fluidized and maintained in the state of fluidization, so that chamber 3' may be discharged.

In view of the fact that the gas and the material being processed flow concurrently in heat exchanging column 1, the thermal efliciency of said heat exchanger may be increased by connecting in series a number of heat exchanging columns to form the heat exchanger shown in FIG. 3. In this case, separate concurrent heat exchanging columns 1 are to be connected so as to obtain a countercurrent flow of gas entering said composite heat exchanger as shown by arrow A and leaving it as shown by arrow A, and of the processed material entering and leaving said composite heat exchanger as shown by arrows B and B'", respectively. To this end, overflow branch pipe 10' of chamber 3' is to be connected to heat exchanging column 1 of the next stage of processing the material, whereas branch pipe that feeds the gas to said heat exchanging column 1 is to be connected to branch pipe 8, through which the gas leaves cyclone 2 of the preceding stage.

Depending upon the temperature of the gas and material fed into heat exchanging column 1, the heat exchanger may be used for both heating and cooling the material.

In the description of thespecific embodiment of the present invention specific terminology has been used for the sake of clarity. The invention, however, is in no way limited by the terminology used, and it should be borne in mind that each specific term employed embraces all the equivalent elements that function analogously and are used for solving identical problems.

Although the present invention has been described with reference to the preferred embodiment thereof, it will be readily understood that various changes and modifications may be resorted to without deviating from the spirit and scope of the invention.

These changes and modifications shall be considered as falling within the spirit and scope of the invention as disclosed in the specification and appended claims.

We claim:

1. A heat exchanger for powdered materials suspended in gas comprising at least one heat exchanging column; a cyclone connected to said column and being positioned after said column in the direction of the flow of said powdered material; a discharging chamber positioned beneath said cyclone, said chamber being provided with a partition which does not reach the chamber bottom and divides said chamber into two compartments, said compartments communicating between said chamber bottom and the lower edge of said partition, the first compartment communicating with said cyclone and adapted to contain a dense layer of said powdered material discharged therefrom and form a seal for said cyclone, the second compartment being provided with outlet means and-means for fluidizing powdered material from said first compartment such that said fluidized powdered material is adapted to be discharged through said outlet means.

2. A heat exchanger as claimed in claim 1 wherein said means for fluidizing is an air distribution device connected to the bottom of said second chamber.

References Cited UNITED STATES PATENTS 2,799,558 7/1957 Smith et al. 23l42 2,903,800 9/1959 Skoglund.

2,915,365 12/1959 Saussol.

3,263,346 8/ 1966 Vandenhoeck.

FREDERICK L. MATTESON, IR., Primary Examiner.

R. A. DUA, Assistant Examiner. 

